This snippet hides the WordPress version update message that is displayed when there is a new version of WordPress available.

Instructions
Ad this to your functions.php file.

<?php if ( !current_user_can('administrator') ) {
    add_action( 'init', create_function( '$a', "remove_action( 'init', 'wp_version_check' );" ), 2 );
    add_filter( 'pre_option_update_core', create_function( '$a', "return null;" ) );
} ?>